The problem of determining an objective means for assessing local characteristics of television subpictures in a Hadamard transform multicoder scheme is stated and discussed. Detailed investigations of transform domain coefficient statistical characteristics for different test images have been conducted. Both monochrome and colour signals were used, as well as different transform sizes and shapes. " Directing Indexes " are proposed which, depending on the inter-relationships among transform coefficients and groups of coefficients, direct each subpicture to the appropriate coder. Three indexes in the case of monochrome signals are proposed, each with its own computational procedures and application requirements. Necessary modifications and changes for application of some indexes on colour signals are also discussed. The proposed technique of indexing eliminates the necessity of equal distribution of subpictures among 'activity classes', a major disadvantage encountered in present activity index. Coders to be used with each directing index are devised and tested, subject to an arbitrary bit rate of 2 bits per pixel, with satisfactory performance compared with some published results for other techniques.

No description available.

In this thesis, one finalist cipher of the Advanced Encryption Standard (AES) block cipher contest, Twofish proposed by Schneier et al, is studied in order to observe the validity of the statement made by Arikan about the randomness of the cipher, which contradicts National Institute of Standards and Technology (NIST)&rsquo / s results. The strength of the cipher to cryptanalytic attacks is investigated by measuring its randomness according to the avalanche criterion. The avalanche criterion results are compared with those of the Statistical Test Suite of the NIST and discrepancies in the second and third rounds are explained theoretically.

München, Techn. University, Diss., 2007.

Thesis (M.S.)--Naval Postgraduate School (Monterey, Calif.), 1991. / Cover title. "September, 1991." Includes bibliographical references (leaves 123-125).

CUNHA, Cleiton Lira. Propriedades de autovalores para uma classe de operadores elìpticos de segunda ordem. 2016. 55 f. Tese (Doutorado em Matemática)- Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Rocilda Sales (rocilda@ufc.br) on 2016-11-28T12:57:01Z No. of bitstreams: 1 2016_tese_clcunha.pdf: 424165 bytes, checksum: 2b61c3ffd4ce2d70541dcc2377d01519 (MD5) / Approved for entry into archive by Rocilda Sales (rocilda@ufc.br) on 2016-11-28T12:57:55Z (GMT) No. of bitstreams: 1 2016_tese_clcunha.pdf: 424165 bytes, checksum: 2b61c3ffd4ce2d70541dcc2377d01519 (MD5) / Made available in DSpace on 2016-11-28T12:57:55Z (GMT). No. of bitstreams: 1 2016_tese_clcunha.pdf: 424165 bytes, checksum: 2b61c3ffd4ce2d70541dcc2377d01519 (MD5) Previous issue date: 2016 / We deal with properties of eigenvalues of a class of elliptic operators in the divergence form on a compact Riemannian manifold M, which we denote by L. When the metric varies analytically on M, we obtain analytic curves of eigenvalues and eigenfunctions of L satisfy Dirichlet boundary condition. We compute Hadamard type variational formula and as application we show that the set of Cr{metrics, such that L has simple spectrum, is a generic set. We prove that the set of Cr{di eomorphisms on a domain in M such that the eigenvalues of L are simples is a generic property too. We also analysis the behavior of eigenvalues when the metric varies through Ricci ow in closed Riemannian manifold, showing, for example, that it increase under suitable hypothesis. We still show that the results of genericity are valid under Neumann boundary condition. / Neste trabalho, estudamos propriedades de autovalores de uma classe de operadores elípticos na forma divergente em uma variedade riemanniana compacta M, ao qual denotaremos por L. Mostramos que, quando a métrica é variada analiticamente sobre M, conseguimos obter curvas analíticas de autovalores e autofunções de L satisfazendo condição de bordo de Dirichlet. Deduzimos fórmulas variacionais tipo Hadamard e como aplicação mostramos que o conjunto das métricas Cr que deixa o espectro de L simples é genérico. Provamos que o subconjunto dos difeomorfismos de classe Cr sobre um domí nio Ω tal que os autovalores de L são simples e residual. Posteriormente, fazemos uma análise do comportamento dos autovalores de L quando variamos a métrica por meio do fluxo de Ricci no caso em que M é fechada mostrando, por exemplo, que são crescentes sob certas hipóteses. Mostramos ainda que os resultados de genericidade ainda são válidos sob a condição de bordo de Neumann.

In this dissertation we study the Lyapunov diagonal stability and its extensions through partitions of the index set {1,...,n}. This type of matrix stability plays an important role in various applied areas such as population dynamics, systems theory and complex networks. We first examine a result of Redheffer that reduces Lyapunov diagonal stability of a matrix to common diagonal Lyapunov solutions on two matrices of order one less. An enhanced statement of this result based on the Schur complement formulation is presented here along with a shorter and purely matrix-theoretic proof. We develop a number of extensions to this result, and formulate the range of feasible common diagonal Lyapunov solutions. In particular, we derive explicit algebraic conditions for a set of 2 x 2 matrices to share a common diagonal Lyapunov solution. In addition, we provide an affirmative answer to an open problem concerning two different necessary and sufficient conditions, due to Oleng, Narendra, and Shorten, for a pair of 2 x 2 matrices to share a common diagonal Lyapunov solution. Furthermore, the connection between Lyapunov diagonal stability and the P-matrix property under certain Hadamard multiplication is extended. Accordingly, we present a new characterization involving Hadamard multiplications for simultaneous Lyapunov diagonal stability on a set of matrices. In particular, the common diagonal Lyapunov solution problem is reduced to a more convenient determinantal condition. This development is based upon a new concept called P-sets and a recent result regarding simultaneous Lyapunov diagonal stability by Berman, Goldberg, and Shorten. Next, we consider various types of matrix stability involving a partition alpha of {1,..., n}. We introduce the notions of additive H(alpha)-stability and P_0(alpha)-matrices, extending those of additive D-stability and nonsingular P_0-matrices. Several new results are developed, connecting additive H(alpha)-stability and the P_0(alpha)-matrix property to the existing results on matrix stability involving alpha. We also point out some differences between these types of matrix stability and the conventional matrix stability. Besides, the extensions of results related to Lyapunov diagonal stability, D-stability, and additive D-stability are discussed. Finally, we introduce the notion of common alpha-scalar diagonal Lyapunov solutions over a set of matrices, which is a generalization of common diagonal Lyapunov solutions. We present two different characterizations of this new concept based on the well-known results for Lyapunov alpha-scalar stability [34]. The first one hinges on a general version of the theorem of the alternative, and the second one using Hadamard multiplications stems from an extension of the P-set property. Several illustrative examples and an application concerning a set of block upper triangular matrices are provided.

Submitted by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-13T15:18:50Z No. of bitstreams: 1 Tese - Raul R. Mesquita.pdf: 2035561 bytes, checksum: c90ee83b92d4f8ba8b3d878144474d4a (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-13T15:19:04Z (GMT) No. of bitstreams: 1 Tese - Raul R. Mesquita.pdf: 2035561 bytes, checksum: c90ee83b92d4f8ba8b3d878144474d4a (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-13T15:19:21Z (GMT) No. of bitstreams: 1 Tese - Raul R. Mesquita.pdf: 2035561 bytes, checksum: c90ee83b92d4f8ba8b3d878144474d4a (MD5) / Made available in DSpace on 2016-12-13T15:19:21Z (GMT). No. of bitstreams: 1 Tese - Raul R. Mesquita.pdf: 2035561 bytes, checksum: c90ee83b92d4f8ba8b3d878144474d4a (MD5) Previous issue date: 2014-07-11 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / In this thesis we consider an analytic family of Riemannian structures on a compact smooth manifold M with boundary. We impose the Dirichlet condition to the Eta-Laplacian and proof the existence of analytic curves of its eigenfunctions and eigenvalues. We next derive Hadamard type variation formulas. As a first application of these formulas we obtain that there is a residual subset of the set of metrics where all eigenvalues of the Eta-Laplacian operator are generically simple. We consider a bounded domain 12 in M. Then we show that the subset of diffeomorphisms in 12 is residual provided the eigenvalues of the Eta-laplacian are simple. As another application we obtain variational expressions of the eigenvalues in the case when the metric varies conformally. We conclude our work with analysis of the behaviour of the eigenvalues of Eta-laplacian along the Ricci flow. / Neste trabalho consideramos uma família analítica de estruturas riemannianas em uma variedade diferenciável M com bordo. Impomos a condição de bordo de Dirichlet ao Eta-laplaciano e mostramos a existência de curvas analíticas de seus autovalores e autofunções. Deduzimos fórmulas variacionais tipo Hadamard. Como primeira aplicação mostramos que existe um subconjunto residual do conjunto das métricas, para o qual todos os autovalores do Eta-laplaciano são genericamente simples. Consideramos ainda um domínio limitado em M, e então mostramos que o subconjunto de difeomorfismos do domínio onde os autovalores do Eta-laplaciano são simples, é residual. Em uma segunda aplicação obtemos, para o Eta-laplaciano, expressões variacionais para os autovalores quando a variação da métrica é conforme. Por fim, é feita uma análise do comportamento dos autovalores do ij-laplaciano ao longo do fluxo de Ricci, onde eventualmente se tem a suavidade da respectiva autofunção.

Consider an m x zero-one matrix A. An s x t submatrix of A is said to be even if the sum of its entries is even. In this paper, we focus on the case m = n and s = t = 2. The maximum number M(n) of even 2 x 2 submatrices of A is clearly ( 2n) 2, and corresponds to the matrix A having, e.g., all ones (or zeros). A more interesting question, motivated by Turán numbers and Hadamard matrices, is that of the minimum number m(n) of such matrices. It has recently been shown that m(n) ≥ 1/2 ( 2n) 2 - Bn 3 for some constant B. In this paper we show that if the matrix A = A n is considered to be induced by an infinite zero one matrix obtained at random, then P(E n ≤1/2( 2n) 2 - Cn 2 log n infinitely often) = 0, where E n denotes the number of even 2 x 2 submatrices of A n. Results such as these provide us with specific information about the tightness of the concentration of E n around its expected value of 1/2 ( 2n) 2.

Hyperspectral imagery is often associated with high storage and transmission costs. Dimensionality reduction aims to reduce the time and space complexity of hyperspectral imagery by projecting data into a low-dimensional space such that all the important information in the data is preserved. Dimensionality-reduction methods based on transforms are widely used and give a data-dependent representation that is unfortunately costly to compute. Recently, there has been a growing interest in data-independent representations for dimensionality reduction; of particular prominence are random projections which are attractive due to their computational efficiency and simplicity of implementation. This dissertation concentrates on exploring the realm of computationally fast and efficient random projections by considering projections based on a random Hadamard matrix. These Hadamard-based projections are offered as an alternative to more widely used random projections based on dense Gaussian matrices. Such Hadamard matrices are then coupled with a fast singular value decomposition in order to implement a two-stage dimensionality reduction that marries the computational benefits of the data-independent random projection to the structure-capturing capability of the data-dependent singular value transform. Finally, random projections are applied in conjunction with nonnegative least squares to provide a computationally lightweight methodology for the well-known spectral-unmixing problem. Overall, it is seen that random projections offer a computationally efficient framework for dimensionality reduction that permits hyperspectral-analysis tasks such as unmixing and classification to be conducted in a lower-dimensional space without sacrificing analysis performance while reducing computational costs significantly.